Au and Au-Ag bimetallic nanoparticles synthesized by using 12-3-12 cationic Gemini surfactant as template

A seed-growth method has been applied to synthesize gold (Au) and Au-silver (Ag) bimetallic nanoparticles (NP) by using 12-3-12, a cationic Gemini surfactant, as a capping agent as well as micellar template. A systematic increase in the [12-3-12] from pre- to post-micellar region (up to 5 times the critical micelle concentration, cmc) produces Au NP from spherical to large plate like structures. Keeping [12-3-12] constant (equal to 1 / 2 cmc) and increasing ascorbic acid (AA) concentration lead to the formation of core shell type Au-Ag bimetallic NP. At maximum AA concentration (i.e. [AA] = 5.6 mM), fused bimetallic Au-Ag NP are obtained. The anisotropic growth of such materials is a key factor for various applications in nanotechnology.     

N,N′-二(β-十八酰氧基)乙基乙二胺二乙酸钠的合成及性能研究

用 N,N′-二羟乙基乙二胺、氯乙酸钠合成了 N,N′-二羟乙基乙二胺二乙酸钠(中间体),中间体再与硬脂酰氯反应制备了一种新型 Gemini 两性表面活性剂 N,N′-二(β-十八酰氧基)乙基乙二胺二乙酸钠。对产物合成条件进行了考察,优化的反应条件为:n(硬脂酰氯):n(中间体)=2.5,溶剂 V(水):V(氯仿)=1:2,pH=9.0～10.0,反应温度15～20℃,反应时间5 h。通过红外光谱和质谱分析确定了产物结构,并测试了产物的表面性能。结果表明,在25℃时,该产物的临界胶束浓度为0.24 mmol/L,临界胶束浓度下的表面张力为35.7 mN/m;即时泡沫高度为250 mm,5 min 后泡沫高度为220 mm;乳化时间为22.48 min(甲苯-水物系)和4.65 min(正己烷-水物系),亲水-亲油平衡值为5.4,等电点为 pH 3.3～6.5。     

Surface and Biocidal Properties of Gemini Cationic Surfactants Based on Propoxylated 1,6-Diaminohexane and Alkyl Bromides

Two new classes of gemini cationic surfactants—hexanediyl-1,6-bis[(isopropylol) alkylammonium] dibromide {in the abbreviation form: C_nC₆C_n[iPr-OH] and C_nC₆C_n[iPr-OH]₂; alkyl: C_nH_{2n + 1} with n = 9, 10, 12 and 14}—have been synthesized by interaction of alkyl bromides with N,N′-di-(isopropylol)-1,6-diaminohexane and N,N,N′,N′-tetra-(isopropylol)-1,6-diaminohexane. The surface tension, electrical conductivity, and dynamic light scattering (DLS) techniques were used to investigate the aggregation properties of the gemini cationic surfactants in aqueous solution. The formation of critical aggregates at two concentrations in an aqueous solution from obtained gemini cationic surfactants were determined via the tensiometric method. Thus, these gemini cationic surfactants start to form aggregates at concentrations well below their critical micelle concentrations (CMC). The surface properties and the binding degree (β) of the opposite ion were tested against the length of the surfactant hydrocarbon chain and the number of the isopropylol groups in the head group. By applying the DLS technique, it was explored that how the number of isopropylol groups in gemini cationic surfactants with C₁₂H₂₅ chain affects the sizes of micelles at concentrations greater than CMC. It was discovered that the obtained gemini cationic surfactants have a biocidal character.     

Activity of Bromelain with Cationic Surfactants and the Correlation with the Change of 1H NMR Signals

This study observed the activities of bromelain in the presence of various cationic surfactants at different temperatures and the conformational changes in bromelain by ¹H NMR spectroscopy. We found that the bromelain activity was enhanced by tens to hundreds of micromoles per liter of the surfactant. In the presence of the surfactants, bromelain exhibited good tolerance to a range of substrate temperatures and its thermal stability was also increased. The ¹H NMR experiments indicated that when the temperature was increased from 25.0 to 45.0 °C, the protons of bromelain having chemical shifts (δ) between 3.7 and 5.2 ppm moved upfield, while those having δ values between 3.2 and 3.7 ppm moved downfield. In the bromelain/cationic surfactant mixture, the values of δ for the protons in both bromelain and the cationic surfactants decreased, accompanied by the broadening of the half-peak width of the surfactant protons. These results indicated that both increasing temperature and adding a cationic surfactant made the bromelain chain more flexible and hence, increased the bromelain activity. To the best of our knowledge, this was the first time that the relationship between the protein activity and the ¹H NMR data was expounded.     

DEDS-10双子表面活性剂的性能研究

合成了一种新型的DEDS-10双子表面活性剂,用红外光谱对所合成化合物的结构进行了初步表征。DEDS-10的临界胶束浓度cm c为0.47 mmol/L,γcm c为34.5 mN/m,A lC l3、CaC l2和NaC l可以使γcm c降低3.6~1.1 mN/m,其cm c值大约为纯水溶液cm c值的1/5~1/3;加入乙醇,可增加其表面活性,在乙醇的浓度为0.22 mol/L时,其表面张力为30 mN/m左右。与阳离子表面活性剂DTAB和非离子表面活性剂曲拉通X-100复配,可以大幅度地降低cm c和γcm c值,与阴离子表面活性剂TLS复配时,cm c降低,cγm c略有增加。     

vGemini表面活性剂的聚集行为及应用的新进展

综述了已报道的几种新型Gemini表面活性剂的化学结构，并对它们在气／液、气／固界面及溶液中的聚集行为和应用做了讨论。     

磺酸型Gemini表面活性剂的合成及表面活性

以壬基酚、1,4-二溴丁烷和氯磺酸为主要原料,通过三步反应合成了新型的磺酸型Gemini表面活性剂9BA-4-9BA,讨论了合成反应时间、温度以及催化剂对产物纯度和产率等因素的影响,优化了反应过程。利用核磁共振谱和红外光谱表征了产物结构,并通过DCTA21表面/界面张力仪测试其水溶液中的表面张力。和传统表面活性剂相比,合成的Gemini表面活性剂9BA-4-9BA具有更高的表面活性,其临界胶束浓度和C20分别为6.2×10-4mol/L和1.1×10-5mol/L。     

Gemini表面活性剂的研究现状及其前景

Gem in i表面活性剂具有特殊的结构与性质,所以也就具有了独特的用途。本文从合成、应用等方面系统地分析了Gem in i表面活性剂国内外研究现状,重点介绍了国内的最新研究进展,并展望了其发展前景。     

松香基吉米奇(Gemini)季铵盐的合成与应用

以天然松香、四甲基乙二胺、环氧氯丙烷为原料,制备出松香基吉米奇(Gem in i)季铵盐,成盐最佳温度80℃,酯化最佳温度140℃。产品可用于阳离子分散松香胶乳化剂、农药增效剂、阳离子沥青乳化剂。